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Plainsman 3D, Mother Nature's Porcelain/Stoneware

We have discovered that, if PR3D is slurried and sieved to 325 mesh, a plastic, ready-to-use porcelain for the 6-8 is produced. One that fires to steel-like strength. And fits common glazes. Even with no processing at all, just slurrying the raw lamps, it produces a stoneware that vitrifies by cone 8 and continues to fire stable and clean across a wide range (even beyond cone 10).

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Plainsman PR#3D Stoneware fired bars

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These PR3D bars are made for the SHAB test. The top one is cone 10 Reduction. Below that, cone 10 down to 5. The clay has been ground to 42 mesh, that standard size at Plainsman Clays. Notice that in reduction firing (top bar) there are almost no iron specks! And it has fired dense, to a porosity below 0.5%. At cone 10 oxidation the porosity is 0.8%. Drying shrinkage is between 5 and 5.5%. Fired shrinkage at cone 10 is less than 7%. At cone 7 it is a stoneware, having only 6% firing shrinkage and 3% porosity. This data is amazing because it is an unprocessed clay, merely ground in a hammermill to break up the lumps.

Mel Noble at Plainsman Clay's Ravenscrag, Saskatchewan quarry

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Six different sedimentary clays are extracted from this quarry. It was opened in the 1970s, the best location available at the time. These test bars were made by slaking select lumps from each layer (thus exhibiting their best performance). The left-most dried test bars show the layers (top to bottom). The A1 top layer is the most plastic and has the most iron contamination (it is used in our most speckled reduction firing bodies). A2, the second one down, is a ball clay (similar to commercial products, although darker burning), it is very refractory and the base for Plainsman Fireclay. A3, third from top, is a complete buff high-temperature stoneware (like H550), although sandy and over-mature at cone 10. 3B, third from bottom, is a smooth medium-temperature stoneware; it contains significant natural feldspar (although fired color and particulate contamination are the most variable). The second from the bottom, 3C. fires the whitest and is the most refractory (it is the base for H441G). The bottom one, 3D, the best product in the quarry. Although the least plastic and most silty, it is also very fine particled and the cleanest (consistently free of particulate impurities and sand), it pairs very well with a ball clay to make a cone 6 stoneware.

Ceramic tiles from Alberta and Saskatchewan clay deposits

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The front tile was fired vitreous and strong at cone 01 (2050F) from a clay mined in Elkwater, Alberta (98Mix). It is fine grained and plastic, clean and low in soluble salts. The back tile is made from a silty clay from Ravenscrag, Saskatchewan (3D). It fires vitreous at cone 6 (2200F). The glaze on that tile is made using a high percentage of another clay similar to 98Mix, it melts at the higher temperature of 2200F. These tiles have dried and fired flat despite the fact they were made from plastic clay (rather than dust pressed).

How is it possible for the same body to work well at both cone 04 and 6!

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Plainsman 3D! White cone 04 bodies are not vitreous and strong and neither is this. But it is plastic, smooth and fits common low fire glazes. How? 15% Nepheline Syenite (also 50% Plainsman 3D, 35% ball clay and 3% bentonite). The unmelted nepheline particles impose their higher thermal expansion on the fired ceramic. Spectrum 700 clear glaze does not craze and does not permit the entry of water (the mug is glazed across the bottom and fired on a stilt). The mug on the right is made from the same clay, it has been fired ten cones higher, cone 6! Here the nepheline is acting as a flux, producing a dense and very strong stoneware (with G2926B, GA6-B glazes). This is incredible! One note: This cannot be deflocculated and used for casting, soluble salts in the 3D gel the slurry.

GA6-C on a light and dark burning clay body at cone 6

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Left: Plainsman 3D, a raw quarry material that fires as a buff stoneware at cone 6-8. Right: Plainsman Coffee clay (stained black using raw umber). Both were fired using the C6DHSC firing schedule. The inside glaze is the GA6-B Alberta Slip base. As of Dec/2021 cobalt retails at $100/500g! Yet the deep blue color on the mug on the right contains zero cobalt, the color is from titanium and iron. This GA6-C blue happens with any dark burning body, or with light burning ones having a dark engobe (e.g. L3954B with a dark colored stain) under the glaze.

Mother Nature's porcelain and stoneware

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These are Plainsman PR3B and PR3D. The 3B bars are fired from cone 8 down to 2 (top to bottom) and the 3D ones from cone 9 down to 3. The 3B has added Nepheline to achieve zero porosity below cone 4 (to make an even better MNP). When plus 325 mesh particles are removed from the 3D is becomes quite plastic, suitable as a stoneware by itself (which we call MNS). And it reaches zero porosity around cone 6. 3D is lighter burning and cleaner, 3B is more vitreous and plastic.

Inbound Photo Links

This super-vitrified clay bodies does this when fired

Links

Projects	Making a high quality ceramic tile
URLs	https://plainsmanclays.com/3d Plainsman 3D Clay Data/Information Page
URLs	https://insight-live.com/insight/share.php?z=s4Wzfu6Qs1 2020 testing project on the incredible clays of central southern Saskatchewan

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